Spray nozzles are used for many various purposes, including industrial spraying operations. Certain industrial spraying applications, in particular the lubrication of conveyor belts, require that a lubricant, typically soap based, be sprayed at low flow rates such as one-to-five gallons per hour. Applications utilizing these spraying nozzles often demand relatively narrow spray angles, and as a result, small metering orifices are required. However, the use of small orifices when combined with low flow rates often leads to clogging problems, especially when dealing with lubricating solutions in which particulate matter is present in the lubricant. Accordingly, particulate materials often build up and clog the nozzle, and it is often necessary to clean the nozzle to resume proper spraying operation.
Some nozzles are designed to facilitate manual cleaning. For example, one such nozzle discloses a valve designed to be lifted with a screwdriver for cleaning. While at times desirable, in certain applications, such as with a large number of spraying nozzles, manual valve cleaning is time consuming and can be dangerous.
Another way to dislodge particulate matter accumulated in the nozzle is to have a self-cleaning nozzle, whereby an increase in the fluid pressure causes a poppet valve to lift itself and attached sealing means away from a special housing containing the metering orifice. This results in a change in the outlet dimension of the metering orifice so that particles clogging the nozzle can become dislodged by the fluid flow.
U.S. Pat. No. 5,033,676 demonstrates one such nozzle. This nozzle comprises a dual mode poppet valve with a head carrying a seal designed to rest against the surface of a housing. In the flushing mode, the head and seal lift to create an unrestricted orifice under a high fluid pressure. Under a lower pressure, the seal rests against a surface in the housing in order to form a restricted orifice.
With this design, however, a special housing must be custom machined, since the restricted orifice is defined by where the seal of the poppet head seats on the surface of the housing. As a result, in order to provide a controlled spray, the housing must be designed to provide a surface that properly mates with the seal as well as being carefully notched in its interior surface to provide a metering orifice.
Since a notch cut into the interior of the housing at the seal is responsible for the spraying pattern, the entire housing must be replaced in order to change the pattern. Thus, with such a design, the spraying pattern cannot be easily and inexpensively modified.
Additionally, means must be machined into the fitting allowing the head and attached valve stem to slide upward but not out of the housing. Finally, the exterior of the housing must somewhat resemble a hose fitting so that hoses feeding the fluid source to the fitting can be easily attached. Such a housing is both expensive and difficult to manufacture, and is dedicated to a single nozzle design.